EP 0180250 B1 19891102 - DIGITAL IMAGE CORRECTION FOR CATHODE RAY TUBE DISPLAYS
Title (en)
DIGITAL IMAGE CORRECTION FOR CATHODE RAY TUBE DISPLAYS
Publication
Application
Priority
US 61450984 A 19840529
Abstract (en)
[origin: EP0180250A2] A digital electron optics correction circuit for correcting focus and astigmatism in a displayed image on a CRT is disclosed. The circuit includes a clock generator for generating a selected number of pulses between each horizontal blanking synchronization pulse. These clock pulses are then counted by an X-address counter and a first address signal is generated corresponding to a particular horizontal position on the CRT screen for each count of the X-address counter. A pulse generator circuit is also provided which is coupled to receive the vertical blanking synchronization pulses and which provides a selected number of output pulses for each vertical banking synchronization pulse. A Y-address counter counts the output pulses from the pulse generator circuit and provides a second address signal corresponding to a particular vertical position on the CRT screen for each count. These X- and Y-addresses are then put to focus and astigmatism ROMS which are preprogrammed with an appropriate control correction signal for each X-Y-address. In a first embodiment of the invention, the pulse generator circuit includes a dividing circuit which is coupled to receive the horizontal blanking synchronization pulses. The dividing circuit then provides an output pulse for every N2 pulses received, and each such output pulse is then utilized to increment the Y-address counter. In a second embodiment, the pulse generator circuit includes a second clock generator for generating N3 pulses between successive vertical blanking synchronization pulses, with each clock pulse being used to increment the Y-address counter. Also disclosed is a specialized clock generator circuit for generating a preselected number of pulses between successive gating pulses.
IPC 1-7
IPC 8 full level
CPC (source: EP US)
H04N 3/26 (2013.01 - EP US)
Designated contracting state (EPC)
DE FR GB IT NL
DOCDB simple family (publication)
EP 0180250 A2 19860507; EP 0180250 A3 19870722; EP 0180250 B1 19891102; CA 1241469 A 19880830; EP 0166254 A2 19860102; EP 0166254 A3 19860409; JP H0344712 B2 19910708; JP S60261264 A 19851224; US 4598234 A 19860701
DOCDB simple family (application)
EP 85114911 A 19850529; CA 480296 A 19850429; EP 85106605 A 19850529; JP 11633085 A 19850529; US 61450984 A 19840529